Theta Trianguli Australis

θ Trianguli Australis, Latinized as Theta Trianguli Australis, is a single^[6] star in the southern constellation of Triangulum Australe. It is visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of +5.50.^[2] The star is located about 345 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +11 km/s.^[1]

Theta Trianguli Australis

Credit: An artistic illustration of Theta Trianguli Australis
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Triangulum Australe
Right ascension	16h 35m 44.82105s[1]
Declination	−65° 29′ 43.4386″[1]
Apparent magnitude (V)	+5.50[2]
Characteristics
Spectral type	G8-K0 III[3]
U−B color index	+0.73[2]
B−V color index	+0.93[2]
Astrometry
Radial velocity (Rv)	11.14±0.12[1] km/s
Proper motion (μ)	RA: +45.577 mas/yr[1] Dec.: +34.381 mas/yr[1]
Parallax (π)	9.4515 ± 0.1434 mas[1]
Distance	345 ± 5 ly (106 ± 2 pc)
Absolute magnitude (MV)	+0.46[4]
Details[4]
Mass	2.65±0.1 M☉
Radius	10.4±0.2 R☉
Luminosity	64.6±1.5 L☉
Surface gravity (log g)	2.81±0.056 cgs
Temperature	5,071±30 K
Metallicity [Fe/H]	0.01±0.026 dex
Other designations
θ TrA, CPD−65° 3331, FK5 3312, HD 148890, HIP 81252, HR 6151, SAO 253614[5]
Database references
SIMBAD	data

This is an evolved G/K-type giant star with a stellar classification of G8-K0 III.^[3] This star is 2.6 times more massive than the Sun, but has expanded to ten times the radius of the Sun. It is radiating 65 times the Sun's luminosity from its photosphere at an effective temperature of 5,071 K.^[4]

References

1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
3. Houk, N.; Cowley, A. P. (1975), University of Michigan Catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor, MI: Department of Astronomy, University of Michigan, p. 452, Bibcode:1975mcts.book.....H.
4. Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (2022-01-01), "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars", Astronomy and Astrophysics, 657: A87, arXiv:2201.01528, Bibcode:2022A&A...657A..87O, doi:10.1051/0004-6361/202040078, ISSN 0004-6361 Theta Trianguli Australis' database entry at VizieR.
5. "tet TrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-29.{{cite web}}: CS1 maint: postscript (link)
6. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.